Life and death are defined by clear differences in physiological state, and so distinguishing between the two is fairly simple. But what about the separation between life, death, and the persistent vegetative state, a prolonged state of deep unconsciousness, characterized by wakefulness in the absence of awareness?

Kurt Gray, head of the Mind Perception and Morality laboratory at the University of Maryland, and colleagues from Harvard University recently explored this question, examining peoples’ perceptions of the vegetative state. What they found—that people perceive the minds of vegetative patients as more dead than the minds of the actual dead—was shocking. Here, in response to questions posed by Britannica science editor Kara Rogers, Gray sheds light on this seemingly paradoxical finding.

Britannica: Could you briefly describe the three experiments you performed in order to determine peoples’ perceptions of life, death, and the persistent vegetative state (PVS)?

Gray: In three studies, we examined peoples’ perceptions of those in a PVS. In the studies, we asked people to rate the mental capacities (e.g., emotion, personality, memory) of a man, “David,” who was in a car accident. Some people read that the David was injured but fully recovered; some read that David died; and some read that David fell into a PVS. This study revealed that people ascribed more mental capacity—or mind—to David when he was dead than when he was in a PVS. In the second study, we examined why this effect occurs. In the third study, we found that people see PVS as worse than death—they would rather die than enter into a PVS.

Britannica: Why do such perceptions exist?

Gray: The reason for this effect is the power of dualism—the perceived separation of mind and body. So while modern science tells us that we are our brains and that’s it, people have a deep-seated intuition that there is something more, that we have a mind/soul in addition to our body. Dualism means that the more we focus on the body, the less we perceive someone as a mind. One oft-cited example is sexual objectification, where focusing on someone’s body leads people to ascribe less mind to them.

In the case of PVS, focusing on the body leads people to ignore their mental capacities. On the other hand, in death, we tend not to dwell on bodies, but instead focus on people’s minds. So while someone in heaven may be thinking, a body in a bed surrounded by beeping machines seems to be thinking of nothing.

We tested this in a study where we asked people to rate the minds of a PVS David, dead David, or corpse David, where we emphasized the body in death. As predicted, emphasizing the body in death lead to reduced perceptions of mind, but only for those who people who did not strongly believe in the afterlife. Those who explicitly believed in the soul (i.e., highly religious people) continued to ascribe mind to the dead, even in the “corpse” condition.

Britannica: The decision to continue or withdraw life support, and who should make that decision, for vegetative patients is highly controversial, and as your research indicates, is heavily influence by personal perceptions. Should, or is it even possible, for such decisions to be made without the influence of perception?

Gray: It would be nice to think that there is an objective answer to whether someone possesses a mind. Certainly, technologies like neuroimaging and EEG (electroencephalography) can tell us how peoples’ brains are reacting to stimuli. But though our brains make our minds, we still don’t know exactly how this occurs. A brain scan could tell us that a person’s brain is putting out theta waves (brainwaves associated with sleep and dreaming). But does this mean they have a mind? Suppose that your brain scan told me that you were unconscious when you actually were conscious. Who’s word would we take? Yours, of course, since we are most concerned with what you think.

And that’s why PVS patients pose so much difficulty when it comes to mind and morality. They cannot speak and tell us about their minds. This is also why people debate the mental and moral qualities of animals—animals cannot tell us that they are conscious. In the absence of self-reports, then, questions of morality lie in how we perceive the minds of others. Because such perceptions are ambiguous, it gets us into this moral muddle.

Britannica: Perception has an extraordinary influence on the decisions we make and on what we view as being morally right or wrong. Do our perceptions have moral consequences?

Gray: I would suggest that perceptions are morality. Our moral judgments really depend on how we perceive the minds of others, and it is difficult imagining cases where they are consistently different. For example, imagine someone saying about a fetus: “I think it can think and feel, but abortion is permissible.” Morality is just as much a matter of perception as how we see the minds of others, and much of my research suggests that they are the same thing.